Atomistic modelling of reversible phase transformations in Ni-Ti alloys: A molecular dynamics study

摘要

Ni-Ti thin films for micro actuators is the focus of intense research. Such films have precipitates with a unique micro-structure. By molecular dynamics simulation (MDS) using embedded-atom potentials, we construct nano-sized Ni-Ti model systems including plate shape precipitates. First, the energetics of such plate precipitates is evaluated. The simulations show that there is a lower energy precipitate which is actually observed in experimental studies. Second, uniaxial-tensile loading is conducted for the MDS model which contains the precipitate. For the relaxed state, the precipitate sufficiently matches the Ni-Ti parent phases at the interfaces, whereas during the loading, mismatch as well as nucleation of martensite occurs there.